Echolocation beam focusing in the false killer whale (Pseudorca crassidens)
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1
University of Hawaii, Hawaii Institute of Marine Biology, United States
The sound production system of odontocetes contains a fat-filled melon which has been assumed to help focus the emitted sound beam. Despite the presence of this structure, odontocete echolocation signals are typically modeled as unchanging beams because active beam focusing has not been demonstrated empirically. Using a 16-channel hydrophone array system and custom analysis algorithm, we measured the size of the echolocation beam of a false killer whale performing a discrimination task to determine whether the size of the beam varies under different echolocation conditions. The animal performed an “easy” and a “hard” discrimination task with targets at distances of 2.5, 4, and 8 m. ANCOVA results indicate that beam size changes depending on click frequency, target distance and target difficulty. Regardless of frequency, the whale changes the size of her emitted echolocation beam according to target distance and difficulty. We propose the whale is using a strategy of creating and adjusting the focal region of her echolocation beam, which would provide maximum energy return of the target echo.
Acknowledgements
This research project was supported by the Office of Naval Research (grant
NOO14-08-1-1160 to P.E.N.). The authors thank all the members of the Marine Mammal Research Program
group, including Alexander Supin and Whitlow Au, for their continuous assistance, and thank Ted Cranford for valuable input.
Keywords:
beam focusing,
Echolocation,
odontocete
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster (but consider for participant symposium and student poster award)
Topic:
Sensory: Audition
Citation:
Kloepper
L,
Nachtigall
P,
Donahue
M and
Breese
M
(2012). Echolocation beam focusing in the false killer whale (Pseudorca crassidens).
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00161
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Received:
27 Apr 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Ms. Laura Kloepper, University of Hawaii, Hawaii Institute of Marine Biology, Kailua, United States, lkloepper@saintmarys.edu